How do I make the ends shorter?
your faces may keep overlapping if you're moving geometry by extruding, E to extrude when you want to CREATE new geometry but use G (optional: and then an axis (x,y,z)) to only move the geometry you currently have (and have selcted).
I hope you found this helpful :) and good luck on your project!
Blender can be confusing at first but it's well worth the struggle, don't give up!